The conventional drivers and spoons which are made of persimmon wood are becoming less popular than newer metal wood heads.
Most of such metal heads (hereinafter referred to as the heads) have been made of cast stainless steels or aluminum alloys utilizing a precision casting process known as the lost-wax casting process.
However, so long as the heads are made by a casting method, it is impossible to avoid producing defects such as porosity and segregation, and consequently, it would be difficult to produce high quality heads consistently.
Further, the cast metal heads (hereinafter referred to as cast heads) are often made of relatively large grained material of over 0.5 mm, representing relatively poor yield and tensile strengths, and coupled with the above mentioned porosity and segregation defects, the golf heads available today are of relatively inferior mechanical qualities. Given such basic disadvantages of cast materials, it was difficult to achieve the desirable balance between the ideal size and weight of a head, and the cast heads exhibited the characteristics of small area of the sweet spot and poor directional stability of a flying ball.
Further, the cast heads required the sole portion to be attached with machine screws or brazing, requiring a number of manufacturing steps, and the balancing weight too had to be attached after the fabrication steps, thus complicating the overall manufacturing process.
The object of the present invention is to present a manufacturing method for metal golf club head having desired thin walls, increased flight distance and improved directional stability.
Still another object of the present invention is to present a metal head manufacturing method which permits: simplification of the manufacturing steps; simple attachment of balancing weight; and improved finishing of the joints.